Tape reader and control system

ABSTRACT

A system providing for improved local and remote control over operation of a tape reader. The controls being operative to selectively initiate and automatically terminate both the reading and omission of data, with the omission operations being effected at a higher rate than the reading operations. These controls also being operative to automatically inhibit reading operations for various time intervals when the unit is supplying a teleprinter and particular mechanical commands are being executed by the teleprinter.

United States Patent [72] Inventors John J. Larew;

Paul J. Moran, both of Waynesboro, Va. [21 Appl. No. 789,841 [22] FiledJan. 8, 1969 [45} Patented Nov. 23, 1971 [73] Assignee General ElectricCompany [54] TAPE READER AND CONTROL SYSTEM 28 Claims, 12 Drawing Figs.

[52] 11.8. CI 178/17 R, 197/20 [51] lnt.C1 1-1041l7/l2 [50] Field ofSearch 178/17, 17 A, 17 B, 23, 23.1, 79, 80, 81, 17.5; 197/20; 3401174.]A, 174.1 K

[56] References Cited UNITED STATES PATENTS 3,414,103 12/1968 Knudsen eta1. 197/20 3,333,668 8/1967 Sausele 197/20 3,291,277 12/1966 Borrelli eta1. 197/20 3,280,256 10/1966 Clark et al. 178/179 3,219,165 11/1965Greene et al. 197/20 RUN STOP STOP RAPID ADVANCE READER CONTROLS2,905,299 9/ 1 959 Hildebrandt 197/20 2,905,298 9/1959 Blodgett et al197/20 2,894,614 7/1959 Lambert et al. 197/20 2,865,487 12/1958Hildebrandt 197/20 2,700,446 l/l955 Blodgett 197/20 3,417,202 12/1968Kolpek 178/31 3,403,225 9/1968 Mislan et al. 179/2 3,353,744 11/1967Becking et al. 197/20 Primary Examinerl(athleen H. Claffy AssistantExaminer-Tom DAmico Anorneys- Lawrence G, Norris, Michael Masnik, FrankL.

Neuhauser and Oscar B. Waddell TAPE READER TELEPRINTER ADVANCE AND READGATES DATA GATES |-24 PUNCH DECODER SHORT DELAY COMPA R.

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JOHN J. LAREW PAUL' J. MORAN THEIR ATTORNEY PATENTEUuuv 2a IHTI SHEET 7[IF 7 INVENTOR. JOHN J. LAREW PAUL J. MORAN THEIR ATTORNEY @Ww NE? FEEBACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to readers for stored ,data; more particularly, itconcerns a system that provides automatic control of a reader andpermits both automatic and manual control of the storage medium editingfunctions.

The rapidly expanding field of communications relies more and more uponautomatic data-handling equipment. Such equipment must be capable ofaccurate and extremely fast transmission and reception of data. By theelimination of manual operations, it has been found that not only speedbut also reliability can be increased. Oftentimes, data-handling systemsinclude the use of either magnetic or punched recording media. Therecording medium is run through reading equipment in order to interpretits contents and control operation of suitable transmitting orutilization equipment.

2. Description of the Prior Art Both magnetic and punched tape recordingsystems utilize binary codes to record information. According to suchusage, the presence or absence of a magnetic bit or a hole" isrepresentative of a logic 1 or logic 0. A large number of code systemshave been developed using discrete permutations of a particular numberof bits to represent specific numeric, alphabetic, and commandcharacters. The system adopted for a particular use depends upon therequirements peculiar to that use. It may also be stated that generally,the selection of magnetic or punched recording media is also dependentupon the peculiarities of each use. In many cases, the media are directequivalents of one another.

At the present time, recorded data is used extensively intelecommunications, machine tool control, accounting, and computing. Inaddition, it is being used with increasing success in the officeequipment field. Teleprinters and typewriters are now used to convertdata from coded tapes to conventional language texts. n the other hand,data is sometimes transmitted in its original form to remote locationswhere it is simply reproduced.

The great advantages of high-speed operation have resulted in thedevelopment of equipment that responds to data much more rapidly thancan be physically monitored by human operators. Thus, parity checktechniques have been developed which permit automatic testing for errorsand which also provide the means for initiating steps to remove theseerrors. Nevertheless, it is still necessary and desirable to providemeans for the override of automatic operation by a human operator inorder to effect editing operations that cannot be stored for automaticimplementation.

Two presently used data-handling systems may be considered in order toappreciate the types of problems the subject invention is intended tosolve.

The first system involves telecommunication wherein a tape controls thedata presented to a teleprinter from a tape reader. The control tape maycontain too much data, undesired repetitive data, or erroneous data. Thepresentation of such data to the teleprinter is undesirable.Accordingly, means must be provided for detecting its presence andselectively omitting it. Existing equipment in some instances offersthis capability; however, undue complications and excessive time areinvolved in accomplishing the desired functions. The control tape mayalso contain original data that is to be replaced with new data. In thiscase, means must be provided for detecting the time of presentation ofthe original data and then efiecting its replacement. Here too, existingequipment offers highly unsatisfactory means for accomplishing thedesired functions.

Similar problems occur in the ofi'rce equipment field whereinautomatically operated typewriters are controlled by tapes developedduring the typing of a draft. In this type of system, the final copy ofa text is developed by permitting the tape to control the typewriteronly when approved passages are being typed. When a portion of theoriginal draft is to be modified, a human operator may override the tapecontrol and manually insert new matter.

SUMMARY OF THE INVENTION The present invention contains a number offeatures of particular value in the systems mentioned above. Althoughthe illustrative embodiment refers to the use of a particular type ofpunched tape, it will be apparent that otherrecording systems can beused, such as magnetic recording, or systems where signals representingcharacters are recorded in a given sequence along a line. For purposesof description, it has been assumed that thetape reader is associatedwith a teleprinter which is responding to the data that is read.Obviously, this specific combination of equipment is also notnecessarily germane to the invention and other equipment may be used inconjunction with the novel elements of the tape reader system andcontrols.

Since the embodiment of the invention described hereinafter functionswith a teleprinter, the ASCII code system has been adopted. It iscontemplated that a punched tape having nine columnsis employed. Sevenof these columns represent bits of a binary code; the eighth column isthe parity check bit; and the ninth column contains sprocket holes. Forpurposes of simplicity, when reference is made to a character, it willbeunderstood that this means a printable character such as analpha-numeric symbol or nonprintable character such as line feed, whichis represented by a particular pennutation of binary indications on thetape. A word" is an assembly of printable characters generally set offfrom the adjacent text by a nonprintable character such as the code SP"(space), or horizontal tab, carriage return or a printable charactersuchas a period. A ?line is a collection of printable characters set offat each end by a nonprintable character such as the code CR" (carriagereturn) or a printable character such as a period, etc. .It is importantwhen responding to a tape reader, particularly with a teleprinter, thatthe tape reader provide adequate timing for thevarious mechanicalfunctions that may be required by the teleprinter. For example, if theteleprinter is commanded to backspace, this is a mechanical operationthat requires a. discrete time. In order to avoid forwarding charactersto the teleprinter at a time when it cannot respond, the tape readermust accordingly be delayed for an appropriate interval. The samesituation is true with respect to other commands such as carriage returnand ribbon change.

An object of this invention is to provide an improved.arrangementfor-reading and editing characters stored along a path in a recordingmedium.

An object of the invention is to provide an improved character reader(i.e., either printable or nonprintable) control systemv including meansfor detecting particular charactersprior to the forwarding thereof tosubsequent equipment.

Another object of the invention is to provide an improved characterreadercontrol system including means for automatically initiatingspecific reader operations upon detection of particular characters.

It will be appreciated that some commands, such as line feed, carriagereturn, etc., require a longer period of time to execute thanl others.In view of this fact, it is desirable to provide variable delays inaccordance with the particular command detected and furthermore, inaccordance with the nature of the next character or characters. In thepast, it has been the practice to follow commands such as line feed LPby a series of nonprintable characters on the tape in order to providethe necessary time delay. With'the present invention, the tape readerequipment automatically responds to detection of a line feed code andconsequently, it is not necessaryto precode a tape to provide thenecessary time delay.

Another object of the invention is to detect particular commands such asmechanical commands of line feed, etc., and effect delays in thetransmission of subsequent printable characters until such commands canbe responded to by the receiving equipment.

ll) IOIISO Yet another object of the invention is to provide fordetection of commands and to provide variable delays in the transmissionof subsequent data depending upon the nature of the subsequent data andthe nature of the command itself.

It is also of value to be able to detect particular characters otherthan the aforementioned printer control characters and initiate specialreader operation in response thereto. For example, a delete (DEL)character is presented on tape by activating all possible bits. Thischaracter is commonly used to erase an erroneously entered character or,in some cases, it is used to provide a time delay for operation ofexternal equipment. It is advantageous to have the option of skippingsuch characters if desired. It may also be desired to skip wholeparagraphs in certain texts. Thus, means foz'filetecting the commandsfor normal paragraph indentation and implementing such skipping are ofvalue. Still further, any such skipping should preferably be carried outat a high rate of speed.

Another object of the invention is to provide an improved tape readercontrol system wherein the detection of certain characters willautomatically initiate high speed operation of reader until detection ofsome other particular character or characters.

When a tape is being read in order to either generate a new tape or totransmit only selected information thereon, it is extremely important tobe able to stop the printer on particular characters, words, or lines.This permits selective editing. Since normal high-speed readingprecludes operator intervention, in effecting this type of editing, itis necessary to determine a target area for the editing by readingspecific portions of the tape at a slow enough speed to ascertain theircontent. Subsequent to this determination, it becomes necessary toprovide means for omitting the desired portions of the tape and/or forpossibly inserting other matter in place thereof.

Another object of the present invention is to provide an improvedcharacter reader control system including means for slowing down thereader and selectively investigating either the next character, word, orline prior to forwarding this data to the connected equipment.

Another object of the invention is to provide an improved characterreader control system having means for selectively and automaticallyomitting characters, words, or lines.

A further object of the invention is to effect omission of any desiredportion of the data on the recording medium at a greater speed than thenormal transmission rate.

Modern telecommunications provide means for requesting the receivingequipment to respond as to whether or not remote parity checking hasestablished that the received data is accurate. Thus, the receivingequipment will send to the transmitting station either a NAK" (notacknowledged) or an ACK" (acknowledged) code if the received data doesnot satisfy parity requirements, or if it does satisfy parityrequirements, respectively. In response to these acknowledgementsignals, the transmitting station either repeats the preceding block ofdata, or proceeds with the transmission. At the remote location, thereceiving unit records the acknowledgement signal on the tape that isbeing generated. Thus, where a block of data is transmitted which doesnot satisfy parity requirements, this block of data will appear on therecording tape followed by NAK." Where the block of data does satisfyparity requirements, it will be followed by ACK." During thereproduction of the tape, it is, of course, desirable not to reproducethe portions which are inaccurate as indicated by the NAK" symbol. Inorder to eliminate these portions, the tape may be run through thereader in a reverse direction and as soon as the NAK" symbol isdiscovered, the portion of the tape between it and the preceding ACK"symbol will be deleted.

It is an object of the present invention to provide means forrecognizing NAK" characters and for subsequently running the reader at ahigh speed until an ACI(" character is detected.

Another important factor in the reading of tapes relates to what wouldappear to be a very simple matter. This concerns the detection of theend of the tape. In the past, this detection has been accomplished bymechanical means.

It is another object of the present invention to provide electronicmeans for detecting the end of tape and to thereafter automaticallyterminate operation of the equipment.

Another object of the invention is to provide means responsive to eitherremote electronic or manual stimulus to reverse the tape within a readerat any desired time.

Further objects and features of the invention will become apparent fromthe following description, which is taken in conjunction with thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a functional block diagramgenerally illustrating the functions carried out by the tape reader anddata utilization device, such as a printer, of the present invention andshowing the relationship between various fundamental functions;

FIGS. 2-9 are individual portions of a logic diagram setting forth anillustrative embodiment of the invention;

FIG. 2 comprises the elements operative to initiate reader operation,control generation of reverse stepping pulses, and respond toteleprinter control during transmission;

FIG. 3 comprises the elements for establishing different delayconditions in response to line feed commands, and the elements fordetecting the tape-out condition;-

FIG. 4A comprises the gates for developing the Advance and Read signalfor the tape reader and the elements responsive to the synchronizingsignal from the teleprinter;

FIG. 48 comprises the elements for initiating and indicating the READNEXT, OMIT NEXT, and BACKSPACE modes of tape reader operation;

FIG. 5 comprises the elements for initiating the selection of character,word, or line discrimination in the READ NEXT and OMIT NEXT modes;

FIG. 6 illustrates typical elements for providing the outputs from eachchannel of the tape reader to the control system and to the associatedequipment;

FIGS. 7A-7C illustrate several typical decoding circuits responsive tothe characters appearing under the head of the tape reader to producecontrol signals;

FIG. 8 comprises the elements for developing forward stepping pulses forthe tape reader, for performing PARITY EDIT operations, and forperforming SKIP DELETES operation; and

FIG. 9 comprises elements operative to permit teleprinter control overthe tape reader in the event that it receives incorrect data.

DESCRIPTION OF THE PREFERRED EMBODIMENT General Description FIG. 1 ispresented to illustrate the basic functions that can be performed by thetape-reading system of the present invention. In this figure, variousfunctions are denoted by blocks and the relationship between the blocksis also depicted. It should be understood that not all of the functionsthat can be performed by the equipment appear in FIG. 1. In order toappreciate the full capability of the system, the reader is directed tothe more detailed circuit description made hereinafter in conjunctionwith the logic diagrams of a particular embodiment.

In the illustrated embodiment, use is made of a punched tape reader thatis responsive to pulses to advance or backspace by one step with eachpulse. Each step places the bits representative of a single character inthe reading posi tion. Thus, the character can be determined and thereader controlled in response thereto. If the character should not beforwarded to connected equipment, the control system will make suitableprovisions. It has been assumed that recording tape provides nine outputindications. These may be developed in the conventional manner withphotoelectric means which detect the presence or absence of the punchedholes in the tape, as well as the sprocket holes. The presence orabsence of a hole is indicated on a respective output lead. When a holeis present, the corresponding output lead provides a signal which willbe considered in the following control logic as being a logic 1 signal.

The tape reader system of the invention can function in four discreteoperating modes. These modes are: RUN, READ NEXT, OMIT NEXT, andBACKSPACE. Pushbuttons are provided to establish each mode of operationand the particular circuit functioning will be described and made clearin connection with the following detailed description of the invention.FIG. 1 relates fonned in the various operating modes.

The Tape Reader 1-10 appears in the upper central portion of FIG. 1. Theoutput of Tape Reader 1-10 which consists of the aforementioned ninesignal leads is applied to a Decoder 1-23 and Data Gate l-24. Decoder1-23 produces binary signals on individual leads. These signals areemployed by the control system to initiate and terminate the variousoperations of the tape reader. The decoder monitors each character as itappears in the reading position on the tape reader.

When it is desired to start operations, Run/Stop circuitry 1- 13 isactivated and provides a start impulse via Reader Controls 1-12 to TapeReader 1-10. When this occurs, the Reader will read the characterappearing in the read position and advance one step. A Teleprinter l-llis illustrated in conjunction with the reader control system. TheTeleprinter 1-11 is responsive to the information presented thereto viaData Gates l-24 and after it has completely digested the information, itreturns a synchronizing signal to Advance And Read Gates 1-25 whichindicates to the Tape Reader control system that a further reading cycleshould be initiated. It should be noted that the first operation of thetape reader requires a start impulse from Run/Stop circuitry l-l3.Thereafter, the Teleprinter, or similar equipment, produces thenecessary synchronizing signals for continuously advancing the TapeReader.

In most situations, the synchronizing signals from Teleprinter 1-11 willsuccessively initiate the reading cycles. However, special Delay means1-27 and 1-28 are provided for delaying the synchronizing signal when apreceding character has commanded teleprinter mechanical operations. Forexample, these delay means .operate when the commands call for abackspace, carriage return, achange in ribbon color, or a line feed. Asa general rule, following any of these four commands, Decoder 1-23activates a Long Delay circuit l-27 which inhibits operation of AdvanceAnd Read Gates 1-25 for the amount of time required to effect thecalled-for mechanical action of the Teleprinter 1-11. After this timehas elapsed, the previously received synchronizing signal fromTeleprinter l- 11 is effective via Gates l-25 to generate the AdvanceAnd Read signal.

It will be appreciated that sometimes the character following the linefeed command will not be a printable character such as a hell, or asecond line feed command. Where this is the case, it is not necessary todelay the reading of this character because the character will notrequire the teleprinter to effect a printing operation. Accordingly, theDecoder 1-23 determines whether or not the succeeding character is aprintable character. In the ASCII code system, printable characters haveeither bit-6, or bit-7, or both b'its present in their code. Thus, thepresence of either of these bits can be easily detected. If a printablecharacter does not occur following an LP, the next line feed ornon-printable character command causes Short Delay l-28 to inhibit thegeneration of the next Advance And Read signal in response to thesynchronizing pulse from Teleprinter 1-11. Thus, it is seen that inorder to completely minimize the delays required by line feed, carriagereturn, etc., two distinct delay circuits are provided in the presentinvention.

In connection with the editing aspects of the invention, attention isdirected to the left-hand portion of FIG. 1. The control system makes itpossible to review the data on the tape before it is forwarded tosubsequent equipment. In most instances this capability is used inconjunction with the high speed omission features of the invention.However, with minor generally to the functions that arepermodifications, this capability can also be utilized in conjunctionwith data addition means.

When it is desired to read the information appearing on the tape inorder to perform possible editing operation, Read Next circuitry 1-16.is activated. Following this, the operator selects circuitry 1-17, 1-18,or 1-1-9, depending upon whether it is the next Character, Word or"Line," which is of interest. When the selection is-made, the equipmentautomatically functions to slow down and read only the desired nextcharacter, word, or line. Assuming that it is the next character whichis of interest, the Character Selection circuitry 1-17 initiates startof the Reader via Advance And Read Gates 1-25 and Reader Controls 1-12.The Tape Reader 1-10 operates to advance and read the next character. Assoon as Decoder l-23 detects a sprocket signal, Comparator means 1-20 isactivated to stop the Reader so that only one character will be read. Asimilar arrangement is provided for reading the next word or line. Thedistinction in operation comes about as a result of having to stop TapeReader 1-10 upon detection of something other than sprocket holes. Thus,when one wishes to read the next word, a start Reader signal isgenerated and the Reader 1-10 will continue operation in response tosynchronizing signals until the Decoder 1-23 detects the presence of acharacter denoting the end of a word. Some of these characters arespace," horizontal tab," carriage return, and line feed." On the otherhand, when one is interested in reading the entire next line, theComparison means 1-19 will permit operation of the Tape Reader 1-10until a carriage return or line feed signal is detected by Decoder 1-23.

Having selectively moved the Tape Reader 1-10 in order to consider thecharacter, word, or line presented thereby, it becomes possible toeffect automatic omission of these characters rather than forwardingthem to connected equipment. When it is desired to omit a character,word, or line. Omit Next circuit l-.15 is activated. In this operatingmode, the Character, Word, or.l..ine circuitry 1-17, 1-18, 1-19, iseffective to function until appropriate codes are detected by theDecoder and used to terminate the particular function being performed. Aspecific unique feature of the invention relates to the provision ofRapid Advance means l-26 which is operative in the event of Omit Nextoperation with Rapid Advance means l-26, rapid advance signals areapplied to Tape Reader 1-10 during omission of data so that is is notnecessary to await the usual slower occurring synchronizing signals fromTeleprinter 1-11, In this way, a minimum amount of time is lost andhigh-speed handling of the data is effected.

This high-speed operation is also called into play when Parity Edit orSkipping Functions are being performed.

In order to understand the functioning of the Parity Edit features ofthe invention, it will be recalled that when tape is initially prepared,it is common to insert the characters NAK and ACK at the end of blocksof data in accordance with whether or not the preceding materialsatisfies parity conditions. When using the Parity Edit feature of theinvention, the tape is inserted in a reverse direction and the Readerl-l0 is started. When the Decoder 1-23 reads a NAK" character, theParity Edit circuitry 1-29 immediately enables Rapid Advance means l-26and the tape advances at a rapid rate without the reading of data untiland ACK" signal is detected by Decoder 1-23. At this time, the Reader1-10 is slowed to its normal operating speed and goes through the normalreading cycles in response to each synchronizing signal received.

The high-speedoperation of the Tape Reader, without forwarding data toother equipment, is also advantageous in implementing the skipping ofundesired portions of data. Such skipping is implemented by Skipcircuitry l-31 which is enabled when a character is detected by Decoder1-23 that signals the start of such undesired portions. The followinglogic schematics illustrate the use of this skipping feature to skipdelete characters. This is of particular value since such characters aregenerally entered on the tape simply to obliterate errors or create timedelays, not required in the advanced equipment IUIUIOB] contemplatedherein. On the other hand, the skipping circuitry can also be activatedby indented material, tables of figures, and any other desired materialthat can be detected by the presence of distinctive characters.

CIRCUIT SYMBOLOGY The logic diagrams of FIGS. 2 through 9 are composedprimarily of flip-flops and NOR logic gates. For convenience inunderstanding the functions of the various components, the flip-flopsare designated with a two-part designation. In this designation, thenumerical prefix represents the figure in which the element appears andthe alphabetical suffix is generally a word or acronym descriptive offunction performed by the flip-flop. For example, flip-flop 2-RUNappears in the left central portion of FIG. 2 and is placed in a setstate in order to initiate the RUN operating mode. Similarly, flip-flop2-SRV appears in FIG. 2 and is placed in a set state to Start Reverseoperation of the Reader. The leads and other elements also bearnumerical prefixes indicative of the figure in which they originate;however, numerical suffixes are used in order to difierentiate betweenthe various elements in each figure.

As a further aid in understanding circuit operation and recognizing theleads over which important control signals are applied, functional leaddescriptions are sometimes used in addition to the numericaldesignations. These functional descriptions are associated with theappropriate leads by means of small arrows. For example, lead 9-18 onthe left edge of FIG. 2 is designated "Trigger Start Reverse." Thisindicates that the signal for triggering the start of reader reversedrive is transmitted by this lead. The bar placed over this functionallead description indicates that the operative signal is a logic 0. Theabsence of such a bar indicates that the operative signal is a logic I.

The NOR logic gates used in the circuitry are of conventional design.The logic function NOR in Boolean Algebra is well known and can bedefined as follows for a two input gate: If one or both inputs have alogic I applied thereto, the output will assume a logic state. Statedanother way, if neither one input nor the other input has a logic Iapplied thereto, the output will assume a logic I state. Two types ofsymbols have been used for illustrating the NOR gates. One of thesesymbols (e.g., see gate 2-16 on the left of FIG. 2) has small circles onthe input leads. This symbol is used where the desired operative outputis a logic I. The other symbol (e.g., see gate 2-20 on the left of FIG.2) has a small circle on the output lead. This symbol is used where thedesired operative output is a logic 0. Although the symbols aredifferent, the gates may be physically the same and they both performthe same NOR operation.

The standard flipflop used in the circuit diagram has five inputterminals and two output terminals. The specific function of eachterminal has been included in the illustration of typical flip-flop 2-R,appearing in the center of FIG. 2. The application of logic l to the setinput will place the flip-flop in a set" state. The application of alogic 1 to the reset input will place the flip-flop in a reset" state.When "set" the flip-flop provides a logic I at its set output and alogic 0 at its reset output. The reverse is true of the reset" state.

Generally, a flip-flop is operated by the application of trigger pulsesto the trigger input. A trigger pulse is one which goes to a logic Icondition. Frequently these pulses are provided in a uniform train froma clock pulse generator. In response to a trigger pulse, a flip-flopassumes the state dictated by the signals on its set steering and resetsteering inputs. The application of a logic 0 to either steering leadwill be effective to switch the flip-flop so that the correspondingoutput provides a logic 1 upon occurrence of the trigger pulse. If thecorresponding output of the flip-flop is already at logic I, no changeof state will occur. It will be noted that the steering leads have smallcircles thereon. This is consistent with the previously noted conventionthat such circles indicate that the operative signals applied to theseleads must be logic 0. Often, the steering leads are shown connected toa circle enclosing a negative sign, or to a ground" symbol. The formerconnection denotes a logic 1 source, and the latter, a logic 0 source.

In keeping with other symbol conventions, the output leads of theflip-flop can be identified by the source. Thus, the lead associatedwith the set output of flip-flop 2-R may be designated 2-R and the leadassociated with the reset output may be designated 2-R.

Consideration will now be given to the detailed logic schematic drawingsset forth in FIGS. 2 through 9. Since the illustrative embodiment of thecontrol system is described in conjunction with a tape readerinterconnected to a teleprinter, the tape reader and teleprinter arerepresented by dashed line boxes at the top of FIG. 2. Each box showsthe pertinent input and output signals associated with typical equipmentof this type.

RUN MODE OF OPERATION Since the teleprinter provides synchronizingsignals for the initiation of tape reading cycles, it is necessary toprovide a start read pulse only at the at the beginning of the RUNoperating mode. Thereafter, the tape reader will receive through thecontrol system, FORWARD STEP signals that are initiated by theteleprinter. On the drawings, the synchronizing signal is labeled RNC(Read Next Character).

Assuming that power has been supplied, the tape reader system is placedin a RUN mode by depressing the Run/Stop button appearing at the upperleft comer of FIG. 2. This removes the logic 1 from the set-steeringinput of flip-flop 2- RUl. Accordingly, on occurrence of the next CPlclock pulse from Clock Pulse Generator 2-CPGI, flip-flop 2RU1 assumes aset condition and a logic 0 appears at the reset output thereof. Thislogic 0 is applied over lead 2-10 to the set-steering input of flip-flop2-RU2. Thus, upon the next appearing CPl clock pulse, flip-flop 2-RU2assumes a set state and provides a logic 1 at its set output. The lattersignal is applied via diode 2-1] as a trigger pulse to the Run flip-flop2-RUN which is connected to be self-steering, i.e., its set output andreset output are interconnected to the set-steering and reset-steeringsteering leads, respectively. Accordingly, the effect of the logic 1signal applied via diode 2-11 is to always switch the state of flip-flop2-RUN. The state of flip-flop 2-RUN indicates whether or not theequipment is to either begin operation or cease operation.

Flip-flops 2-RU1 and 2-RU2 are provided simply in order to prevent anymomentary switch contact bounce of the Run/Stop pushbutton fromeffecting the repetitive operation of flip-flop Z-RUN. Obviously, othermeans could be provided for effecting this operation. As soon as thepushbutton is released, it connects a logic 1 to the reset terminals ofboth flip-flops and they return to the reset condition.

Clock Pulse Generator Z-CPGI provides synchronizing pulses for theentire control system. In the particular implementation of the inventiondescribed hereinafter, the signal provided by the clock pulse generatorwas a 20 microsecond logic 1 pulse that was applied at a repetition rateof approximately l 20 per second.

The four operating modes of the control system are controlled by thecondition of Run flip-flop 2-RUN, Read Next flip-flop 4-RN, Omit Nextflip-flop 4-ON, and the Backspace flip-flop 4-BS. Circuitry is provided,as described subsequently in connection with FIG. 4, to initially placeeach of the four flip-flops in the reset condition. During subsequentoperation of the circuitry, only one of these flip-flops will bepermitted to remain in a set condition at any time. Thus the flip-flopthat is set will establish the mode in which the circuit is operating.

Having set Run flip-flop 2-RUN, it is necessary to generate the startpulse for presentation to the tape reader so that the first read cyclemay begin. This start pulse is generated by the Start Reader flip-flop2-SR appearing in the lower left quadrant of FIG. 2. When Run flip-flop2-RUN is set, a logic l triggering pulse is delivered over lead 2-12 tothe trigger input of Ran flip-flop 2-RA. The set-steering input of Ranflip-flop 2-RA has a logic provided thereto; thus, upon appearance ofthe trigger pulse, flip-flop 2-RA switches to a set state. The switchingof flip-flop 2-RA is effective via NOR gate 2-13 to apply a logic 0 tothe set-steering input of Start Reader flipflop 2-SR. Since the StartReader flip-flop is thereby steered to a set condition, the nexttriggering impulse applied thereto from Clock Pulse Generator 2-CPG II,will set it.

Clock Pulse Generator Z-CPG II provides a signal that assumes a logic Istate at intervals of l2 microseconds and has a duration ofapproximately l.5 microseconds. Obviously, both clock pulse generatorscan be designed in any suitable fashion.

The setting of Start Reader flip-flop 2-SR, supplies a logic I signalvia lead 2-14 to the reset terminal of flip-flop 2-RA, and consequentlyplaces it in a reset condition. The reset output of flip-flop Z-SR isconnected to its reset-steering input. Thus, upon the next occurring2-CP2 clock pulse the Start Reader flip-flop itself will be reset. Thus,during its set condition, the set output of flip-flop 2-SR provides a 12microsecond wide logic 1 signal.

Reference is made to FIG. 8. The logic 1 generated at the set output ofStart Reader flip-flop 2-SR, is applied via NOR gates 8-10, 8-11, and8-12 to the set-steering input of the Step flip-flop 8-STEP appearing atthe center of FIG. 8. As a result of the inversions in each of the NORgates, this set-steering signal is of the appropriate logic 0 state.Thus, upon occurrence of the next CP2 clock pulse on the trigger inputof step flip-flop S-STEP, this flip-flop will be set. The setting offlipflop 8-step is effective through gates 8-13, 8-14, 8-15, and 8- 16to provide a very narrow Forward Step pulse at the output of NOR gate8116. The development of this pulse includes the use of thedifferentiating circuit 8-18 connected between gates 8-14 and 8-15. Thepulse is applied to the tape reader and will cause the tape to beadvanced by one character. As mentioned previously, this is the onlystart pulse that needs to be generated by the control system. Allsubsequent synchronizing pulses will be supplied by the teleprinter whenit is ready to receive the next character.

It will be noted that a number of additional inputs are illustrated forthe various gates thus far encountered. Where necessary, the applicationof signals to these inputs will be described in detail hereinafter.Where the specific mention of these inputs is not made, the source ofthe signals is made obvious by the lead designations. An understandingof circuit operation in response to such signals will be possible sincethe functioning of the circuit elements is easily appreciated. It isbelieved that the specific recitation of the signal paths followed andthe component operation in response to each signal, would unnecessarilyburden the discussion of this illustrative embodiment of the invention.

READER SIGNAL HANDLING AND DECODING Having noted the manner in which theForward Step signal is generated and presented to the Tape Reader, it isworthwhile to consider the nature and handling of outputs from the TapeReader. For this purpose, attention is directed to FIG. 6. The circuitsillustrated in FIG. 6 represent the nine outputs from the Tape Reader.Circuits 1 through 7 provide the 7 coded bits of each character andcircuit 8 provides the parity check bit. The ninth circuit provides thesprocket signal. The first seven channels from the Tape Reader areapplied to transistors 6-11 through 6-17. The outputs of the transistorsare applied to a series of gates 6-21 through 6-27 which inhibittransfer of information to the teleprinter or similar equipment until anenabling signal 8-STEP is provided. This enabling signal is generated atthe reset output of Step flip-flop 8-STEP when the flip-flop is in a setstate.

The equipment is designed to read the character resting in the readerfirst, and then advance the tape by one step to the next characterposition. In order to assure a correct signal being transferred to theteleprinter, it is necessary to provide a strobe pulse which will bedelayed sufficiently after the 5- STEP pulse has opened the gates. Thisstrobe is provided to the teleprinter by a Reader Strobe flip-flop 8-RSappearing in the upper central portion of FIG. 8. The setting of Stepflipflop 8-STEP provides the necessary logic 0 steering signal to ReaderStrobe flip-flop 8-RS. Consequently, upon occurrence of the next CP2triggering signal, Reader Strobe flip-flop 8-RS is set and provides alogic 1 output at its set terminal. This Reader Strobe signal issupplied to the Teleprinter to indicate that the data presented from theTape Reader may be accepted. Upon receipt of all information from theReader, the teleprinter in any known manner will return a signal labeledStrobe In. The Strobe In signal is supplied to the reset terminals ofthe Step and Reader Strobe flip-flops S-STEP and 8- R8 in order to resetthem. At a somewhat later time, after the teleprinter has digested andcompleted its read-in functions, it will provide the necessary RNCsynchronizing signal to reinitiate the read and .advance cyclepreviously described.

Before proceeding with a description of the circuit operating duringnormal response to the various possible commands, reference is made toFIGS. 7A through 7C. These figures illustrate typical decoding circuitswhich operate to provide discrete signals in accordance with thedetection of certain important characters in the reading position at theTAPE Reader. Referring to FIG. 7A, it will be seen that there are sevendiodes. The input to each of these diodes is designated by a number from1 to 7 which is either barred or plain. These input indicationsrepresent the signal bit of the various channels on the tape for aparticular character. Recalling that we have assumed use of the ASCIIcode system, it will be seen that a discrete output is provided fromthis particular decoding circuitwhen. a logic 1 appears at the terminallabeled sprocket," and with the character I l l l l l l appearing on thetape. This isthe delete character in which all possible holesarepunched. Under this condition a logic I signal will be provided onthe lead marked EL" and a logic 0 will be provided on the lead markedDEL."

Other typical decoding circuits are shown in FIG. 7B and FIG. 7C. In thecase of FIG. 78, when the character that is read has the binary code0l0l000, a logic 1 will appear on the lead labeled LF." This indicatesthat the character is a Line Feed command in accordance with the ASCIIcode designations. Similarly, when' the character is 01 10000, a logic Iwill appear on the ACI(" lead. This indicates that an acknowledgementsignal has been obtained from monitoring equipment and that thepreviously printed data block satisfies all parity conditions. Similardecoding gates are provided for developing positive signals for anyparticular character that will be used in conjunction with theinitiation or implementation of operations by the tape reader controlsystem.

READER DELAY OPERATIONS As previously mentioned, depending upon thecharacter stored in the tape, various actions must be taken by thecontrol circuitry. For example, it is necessary to halt the flow ofcharactersfrom the Tape Reader to the Teleprinter, momentarily afterdelivering a Carriage Return" signal code, in order to permit themechanical carriage return action to be carried out. The delay iseffected by preventing immediate response to the synchronizing RNC pulsefrom the Teleprinter and thereby delaying the generation of .the ForwardStep pulse that is normally supplied to the Reader. The Read NextCharacter flip-flop 4-RNCS appearing in the upper portion of FIG. 4A, incooperation with gates 4-12 through 4-21 provide modifying circuitrywhich will either permit immediate response to the synchronizing pulseor delay the response.

In the lower right quadrant of FIG. 3, there is a timing circuit made upof resistor and capacitor-timing elements and gates 3-10 and 3-11. Thistiming circuit is activated by the output of gate 4-14 in FIG. 4 and theoutput of gate 3-12 in the left center portion of FIG. 3. Long delayflip-flops 3-LD1, 3- LD2, and 3-LD3 function in cooperation with thetiming circuit.

In essence, gate 4-14 operates to provide a logic whenever the Decodingcircuitry detects a change ribbon (ECS), a backspace (BS"), or acarriage return (CR) code. This is illustrated on the drawings by thelogic notation ESC+BS+CR. The logic 0 signal is applied to theset-steering lead of long Delay flip-flop 3-LD1. The RNC synchronizingpulse from the Teleprinter is applied as the trigger to this flip-flop;accordingly, when the RNC pulse is provided, it will set flip-flop3-LD1. The logic l appearing at the output of flip-flop 3-LD1 is appliedvia gate 3-12 to the set-steering input of flip-flop 3- LDZ. Uponoccurrence of the next CP2 clock pulse. flip-flop 3-LD2 will be set. Theresulting logic 0 signal at the reset output of flip-flop 3-LD2 isapplied to the set-steering lead of flipflop 3-LD3, and upon occurrenceof the next CPI clock pulse, flip-flop 3-LD3 is set.

The setting of flip-flop 3-LD3 provides a logic 1 signal which resetsflip-flop 3-LD1 via lead 3-13. This signal is also applied to the resetinput of 3-LD2 via lead 3-14. The resetting of the latter mentionedflip-flop removes the set-steering from flip-flop 3-LD3. The resetoutput of flip-flop 3-LD3 is connected to its reset-steering input andit is therefore reset upon appearance of the next CPl clock pulse.

While it is set, the logic I appearing at the set output of flipflop3-LD3 is applied to one input of the gate 3-11. This forces the outputof gate 3-11 to go to a logic 0 for the period of the triggering ofclock signal CPI. The logic 0 signal is applied to capacitor 3-15 inorder to discharge it and reset the timer in the event that it waspreviously in the middle of a timing cycle. At the same time, the logic0 output on the reset output of 3- LD3 discharges capacitor 3-16.

When the next appearing CPl clock pulse resets flip-flop 3- LD3 thenegative going output on the reset output lead is differentiated bycapacitor 3-16 and resistor 3-17 and applied to one input of gate 3-10.This forces the output of gate 3-10 to logic 0 and this is applied toone input of gate 3-11. Since the reset of flip-flop 3-LD3 places alogic 0 on the other input, gate 3-11 provides a logic 1 signal on lead3-40. This marks the beginning of the timing cycle. The logic l signalis applied via a timing circuit comprising capacitor 3-15 and adjustableresistor 3-19 to an input of gate 3-10. This closed loop arrangementmaintains a logic l at the output of gate 3-11 for the duration of thetime interval set by the adjustable resistor 3-19.

Reconsidering again the instant of time at which flip-flop 3- LD3 isset, it will be noted that the set output thereof is applied to gate4-12 in FIG. 4A. This lead will be at logic I and accordingly a logic 0output will be provided from gate 4-12 to one of the inputs of gate4-15. The other input of gate 4-15 is the 3-LD signal from the output ofgate 3-11. It will be recalled that at this time, the 3-LD signal is ina logic 0 state as a result of the resetting of the timer which occursupon setting flip-flop 3-LD3. Thus, a logic I is presented at the outputof gate 4-15 and is applied to gate 4-20 which in turn presents a logic0 to an input of gate 4-21. As will be explained hereinafter, the OmitNext signal 4-ON and the Start Up Reset signal will both be at logic 0at this time. Therefore, the logic 0 output from gate 4-20 will resultin the generation of logic I at the output of ga3e 4-21. This is theAdvance And Read signal that is applied to gate 8-10 to develop aForward Step signal for the Tape Reader. In response thereto, the Readerforwards the ESC, BS, or CR command character to the Teleprinter. It isnow necessary to determine whether or not the succeeding character onthe tape is a printable character. If so, the control system will haveto delay the Reader operation in response to the next RNC synchronizingsignal.

The RNC pulse is received from the Teleprinter at the trigger input ofRead Next Character flip-flop 4-RNCS. This flip-flop is permanentlysteered so that upon receipt of the RNC synchronizing signal, it will beset. As illustrated in the figure, the reset input of flip-flop 4-RNCSreceives the Strobe In signal from the Teleprinter. It is this signalthat indicates the Teleprinter has completed all action in response tothe preceding character. Thus, flip-flop 4-RNCS is automatically set inresponse to the RNC signal and reset in response to the Strobe Insignal.

Gates 4-10 and 4-11 function to determine whether or not a character isprintable. Since printable characters in the ASCII code system haveeither bit-6, bit-7, or both present in their codes, gate 4-10 has inputsignals from channels 6 and 7 of the reader. The operation of gate 4-10results in the presentation of a logic 0 output when either bit-6 or 7is a logic I. The only time this logic 0 output is ambiguous is when thecharacter is delete. In order to eliminate this ambiguity, the Decoderprovides the DEL" signal as one input of gate 4-11. Thus, the output ofgate 4-11 will only be at logic I when there is a printable characterthat is not a Delete, and an RNC signal has previously set flip-flop4-RNCS. The logic 1 output from gate 4-11 is used to drive the triggerinput of Printable Character flip-flop 4-PC. The reset steering input offlip-flop 4-PC is permanently held at logic 1 whereas the set steeringinput is provided with a signal that will be at logic 0 when thecharacter being read is not a space (SP"). Thus, flip-flop 4-PC is setwhen there is a printable character resting in the read position of theTape Reader.

When the timing circuit comprising elements 3-15 and 3-19, in the lowerright portion of FIG. 3, has timed out, signal 3-LD at the output ofgate 3-1 1 will assume a logic 0 state. This logic 0 is applied to oneinput of gate 4-18. The other input of gate 4-18 is connected to thereset output of Printable Character flip-flop 4-PC. Accordingly, ifflip-flop 4-PC is in a set condition indicating that a printablecharacter is ready to be read and that the RNC-synchronizing pulse hasbeen received, the flip-flop will provide a logic 0 to the second inputof gate 4-18. The output of this gate then goes to logic I and theapplication of the logic 1 signal through gates 4-20 and 4-21 results inthe generation of a logic 1 Advance And Read signal.

It will be recalled that the time delay operation just described inresponse to the detection of a Carriage Return (CR") signal by thedecoder circuitry. A similar delay is required in the event of a commandfor either Backspace or Ribbon Change. Where these characters aredetected, logic I signals are applied to gate 4-14 and this is effectiveto initiate the timing cycle just described.

Somewhat different considerations are applicable in the event that thecharacter Line Feed (LF") is detected. In this case, it is necessary todelay reading of any subsequent printable character; however, aspreviously mentioned, the delay I need not be as long as the onepreviously described, if the character or characters between the firstand second line feeds are not printable characters. Thus, if a printablecharacter follows the LF character, it is necessary to start the longertimer just described. On the other hand, if a nonprintable character(e.g., another LF") follows the LF character, a shorter timer may beinitiated, thereby permitting the Teleprinter to rapidly make repeatedLine Feeds.

The signal on the set output of flip-flop 4-PC is applied to the setinput of flip-flop 3-PCLF in the right center portion of FIG. 3. Thereset-steering input of flip-flop 3-PCLF is at a logic 0 when a LineFeed character is detected by the Decoder. Thus, flip-flop 3-PCLF is setif there has been a printable character detected since the last LineFeed command, otherwise it is reset. Flip-flop 3-CLF has itsset-steering input at logic 0 when there is a Line Feed character in theprinter. This flip-flop is triggered by the set output of the Read Nextcharacter flip-flop 4-RNCS. Thus, when the character is a Line Feedcharacter, upon occurrence of an RNC signal from the Teleprinter,flip-flop 3-CLF will be set. When both flip-flop 3-PCLF and flip-flop3-CLF are set, a logic 1 is presented at the output of gate 3-27 whichis effective via gate 3-12 to set steer Long Delay flip-flop 3-LD2. Thenext occurring CP2 clock pulse sets flip-flop 3-LD2 and therebyinitiates operation of the Long Delay Timer as previously described.

If no printable character has been detected since the last Line Feedcommand, it is desired that a shorter time be taken prior to reading ofthe next character. The shorter timing is effected by the timing circuitshown in the upper portion of FIG. 3. The timer consists of flip-flops3-SD1 and 3-SD2, and includes timing circuitry comprising capacitor 3-25and adjustable resistor 3-26.

The conditions for setting the Short Time Delay are established byconnecting the reset output of flip-flop 3-CLF and the set output offlip-flop 3-PCLF to the inputs of gate 3- 20. When both inputs of gate3-20 are at logic 0, it supplies a logic I trigger pulse to flip-flop3-SD1. The permanent set steering of this flip-flop causes it to set inresponse to the trigger pulse, and this in turn set steers flip-flop3-SD2. Flipflop 3-SD2 is set by the next occurring CP2 clock pulse. Thesetting of flip-flop 3-SD2 produces a logic at the output of gate 3-24which is effective to initially reset the timing circuit comprisingcapacitor 3-25 and adjustable resistor 3-26. As was the case offlip-flop 3-LD3, flip-flop 3-SD2 is self-steered to reset and thereforeresets upon occurrence of the next CPZ pulse. This starts the timingcycle. In a reset condition, flipflop 3-.SD2 set steers flip-flop 3-SD3and when the timing cycle has been completed flip-flop 3-SD3 will betriggered to the set state and produce a logic 1 signal at its setoutput. The logic I signal at the set outputof flip-flop 3-SD3 isapplied to gate 4-12 in the same manner that the output of flip-flop 3-LD3 was applied thereto. As a result, an Advance And Read signal will beproduced via gates 4-12, 4-15, 4-20, and 4-21 after the shortened timehas elapsed.

In the event that the longer delay timer is activated prior toinitiation of the shorter delay, the longer timer will override theshorter timer as a result of the action of the 3-LD input to gate 4-15.

All other nonprinting characters that may appear in the tape being readare effective without delay to generate Advance And Read pulses at theoutput of gate 4-21. The circuitry for implementing this generation ofpulses includes gates 4-13, 4- 16, 4-19, 4-20, and 4-21. If thecharacter is nonprintable and not LF, gate 4-13 provides a logic I togate 4-16. Gate 4-16 produces a logic 0 output when the character iseither a Delete or nonprintable or LF." Recall that gate 4-14 produces alogic I only if the character is not ESC," BS," or CR." This being true,inverting the output of gate 4-14 with gate 4- 17 provides a logic 0when the character does not require a Change Ribbon, Backspace, orCarriage Return. The outputs of gates 4-16 and 4-17 are applied alongwith the reset output of flip-flop 4-RNCS to gate 4-19 and will generatea logic 1 output therefrom when nonprinting characters other than thethree specified, are read. This output will produce the Advance And Readsignal via gates 4-20 and 4-21.

TAPE OUT CONDITION It is desirable to stop the Tape Reader when it runsout of tape. Preferably this should be done electronically and not by amechanical sensing means. In accordance with the present invention thiscondition is sensed by noting that repeated forward or reverse steppulses are applied to the Tape Reader without receiving thecorresponding sprocket hole signals which are normally produced when thesprocket hole sensor sees paper and holes alternately.

The impulses commanding forward or reverse steps are not only sent tothe Tape Reader, they are also applied via gates 3- 31 and 3-32 to thetrigger input of Step flip-flop 3-ST appearing in the lower leftquadrant of FIG. 3. Flip-flops 3-ST and 3- T0 are connected as atwo-stage binary counter. When a tape is in place, the step impulseswill register a count and the sprocket signal will reset the counter.The resetting is effected through a plurality of gates 3-33 through3-37. Gates 3-33, 3- 34, and 3-35 insure that the equipment is in one ofits operating modes. Gate 3-36 provides a logic 0 output if theequipment is in one of the operating modes, a Startup Reset signal isapplied, or there is a sprocket signal, A count of two will result inthe setting of Tape Out flip-flop 3-TO. When this occurs the set outputof flip-flop 3-TO is efiective via gates 4-22 through 4-25 in FIG. 48 toreset flip-flops 2-RUN, 4-RN, 4-ON and 4- B8. In other words, thecontrol system is placed in a stop mode.

14 READ NEXT OPERATION Thus far, the circuit operation in response togeneral operating conditions following a start impulse has beendescribed. Attention will now be directed to the specific editingfunctions which the present reader control system is capable ofperforming. The first of these functions involves the controlled.slowing of the Reader in order to determine the next character, word,or line. This is an essential operation preparatory to either acceptingthe information that is to be presented or modifying it in order tocorrect it. At the bottom of FIG. 48 three flip-flops are illustrated.These flip-flops control the operating modes: Read Next, Omit Next, andBackspace, respectively.

The Read Next operation is initiated by closure of the Read Nextpushbutton appearing in the lower left corner of FIG. 4B. This suppliesa logic 1 signal to the set input of Read Next flipflop 4-RN, placing itin a set state. The logic I l signal applied to the set terminal offlip-flop4-RN upon depression of the Read Next pushbutton is alsoapplied via diode 4-28 and lead 4-30 to the trigger input of flip-flop4-ON and 4-BS. The result of this application to the-latter flip-flopsguarantees that they are switched to a reset state in the event thatthey were previously set. It will be noted that the set-steering inputof each of the flip-flops is permanently at. logic 1, whereas theresetsteering terminals are permanently at logic 0.

If it is desired to read only the next character on the tape, and thenstop-the reader, this is accomplished by depressing the characterpushbutton appearing in FIG. 5. The set-steering inputs of each of theflip-flops S-CHAR, S-WORD, and 5- LINE are all connected to the outputof gate 5-13. The inputs to this gate are the 4-RN signal and the 4-ONsignal generated at the set output of the corresponding flip-flop inFIG. 4. Thus, when either the Read Next or Omit Next flip-flops areenergized, a logic 1 will be presented to the input of gate 4-13 and theoutput thereof will be logic 0, thereby set steering the associatedflip-flops. Thus, operation of the character pushbutton applies atrigger pulse to flip-flop S-CHAR and it is set. The consequent logic Isignal appearing at the set output of flip-flop S-CHAR causes a logic 0signal to be produced at the output ofgate 5-14. The inversion inconnected gate 5-15 supplied a trigger pulse to flip-flop 5-OMITappearing on the extreme right of FIG. 5. Flip-flop S-OMIT ispermanently steered to a set condition Accordingly, when it is set, alogic 0 is produced at its reset output and in the absence of an OmitNext signal (4-ON), a logic I CWL start signal will be provided at theoutput of attached gate 5-16. This latter signal derives its name fromthe acronym for Character-Word- Line" start operation.

Referring to FIG. 2, it will be seen that the CWL start signal isapplied via gate 2-13 to the set steering lead of the Start Readerflip-flop 2-SR. Consequently, upon appearance of the next triggerimpulse CP2, a Start Reader signal will be provided at the set output offlip-flop 2-SR and the read cycle previously described will take place.

Flip-flop S-OMIT has the tape out reset signal appearing on lead 3-38applied as a reset input thereto. It will be recalled that these tapeout reset signals are generally developed by the sprocket holes as thetape is read, and appear at the output of gate 3-37 in the lower portionof FIG. 3. After the tape has advanced one character position, flip-flopS-OMIT is therefore reset. The state of flip-flops S-CWLR and S-OMIT arecompared at gate 8-]? in the left portion of FIG. 8. When flip-flop5-OMIT is reset, gate 8-17 provides a logic I which resets Stop Strobeflip-flop 8-58. The resetting of flip-flop 8-SS blocks the incomingAdvance And Read signal that is being applied via gates 8-10, 8-11, and8-12 to the set-steering input of Step flipflop 8-STEP and therebyprevents generation of the Forward Step Signal. This blocking action isefi'ected by the application of the logic 0 from the set output of 8-88to one input of gate 8-19. In order to generate the Forward Step impulseit is essential that one of the inputs to gate 8-19 be in a logic Istate. The other input at this time is at logic 0 state because Runflipll0l056 flop 2-RUN is in a reset state. The logic 0 from flip-flop8-SS makes the output of gate 8-19 a logic I and this prevents the setsteering of flip-flop 8-STEP. The blocking action is very fast and willoccur before the operator removes his finger from the characterpushbutton. When the button is released its back contacts apply atrigger pulse to flip-flop S-CWLR via gates 5-11 and 5-12. The settingof flip-flop S-CWLR results in the application of a logic 1 signal tothe reset inputs of each of the Character, Word, and Line flip-flopsplacing them in a reset condition.

In recapitulation it will be seen that, as a result of depressing theRead pushbutton and the Character pushbutton, a single Forward Stepsignal activated the Reader and the subsequently developed Advance AndRead signal was blocked so that no further Forward Step signals weregenerated.

Consider next the operation of the circuitry when it is desired to readthe next Word. In this instance, after first depressing the Read Nextpushbutton in FIG. 4, the operator depresses the Word pushbutton in FIG.5. Depression of the Word pushbutton results in the application of atriggering impulse to Word flip-flop S-WORD. Once again, it will benoted that this flip-flop is set-steered and therefore it will switch toa set condition. In the present instance, since it is desired than anentire word be read and because more than one character may makeup aword, it is necessary to permit more than one character to be read. Thusthe signal to stop the Reader (i.e., block and Advance And Read signalby resetting flip-flop 8- 88) must be derived not from the sprocketsignal as in the previous case, but from the decoding of one of thenonprinting characters which normally signal the end of a word.Typically, some of these characters are Space," Horizontal Tab, CarriageReturn," and "Line Feed." Other such characters of signals will beobvious to the reader and decoding circuits for detecting the presenceof such characters may easily be developed following the teachings ofthe circuitry shown in FIGS. 7A through 7C.

Gates 8-20 through 8-24 associated with the reset-steering input of theStop Strobe flip-flop 8-SS provide the necessary control for resettingthis flip-flop under the desired conditions. It will be apparent thatthese gates are arranged in order to insure that the flip-flop 8-SS hasa logic 0 signal applied to its reset-steering input when either theWord or Line flip-flop 5- WORD and S-LINE are energized, and there is aCarriage Return, a Space, a Horizontal Tabulation, or an Off signal readfrom the tape. Under these conditions, the subsequently appearingForward Step signal from the output of gate 8-47 will be applied as atrigger pulse to reset Stop Strobe flip-flop 8-SS. In the event that theLine pushbutton is pressed, there is a similar action in order to permitan entire line to be read. In this instance, only the presence of aCarriage Return signal can be operative to block further reading. Thisis effected by means of the gates 8-20, 8-21, and 8-22 associated withthe reset-steering input of the Stop Strobe flip-flop 8-SS. Thus, thegate 8-20 will apply a logic 0 to one input of gate 8-21 when either theLine or Word pushbutton is pressed; in addition, the decoding of a C.irriage Return signal will result in a logic 0 applied to the otherinput. Accordingly, gate 8-21 produces a logic I at the output thereofwhich causes the logic 0 at the output of attached gate 8-22 to resetsteer flip-flop 8-SS.

OMIT NEXT OPERATION Another aspect of tape-editing operations that canbe extremely important is the facility for omitting either the nextcharacter, word, or line in a previously prepared tape. With the presentinvention, this is accomplished by first pressing the Omit Nextpushbutton appearing at the lower central portion of FIG. 4. Thisprovides a logic 1 set signal which switches the Omit Next flip-flop4-ON to a set condition. It simultaneously insures, via suitablyoriented diode 4-31 and lead 4-30, that companion flip-flops 4-RN and4-88 are placed in a reset state. The logic 1 signal appearing at theset output of flip-flop 4-ON is immediately applied to one of the inputsof gate 5-16 in order to prevent the previously described reading actionwhich would be initiated through gate 2-13 in FIG. 2.

The amount of material to be omitted is then selected by operatingeither the Character, Word, or Line pushbuttons in FIG. 5. The operationof the circuitry in response to the subsequently applied signals issubstantially similar to that which occurred when reading was involved.Thus, first flip-flop 5- OMIT is set. Upon setting, the logic 1 signalappearing at the output of flip-flop 5-OMIT is applied to the set inputof Hipflop 8-SS switching it to a set condition. Gate 8-25 is connectedto the reset output of flip-flop 8-SS and it receives a full complementof logic 0 inputs upon the next occurring CPI clock pulse. It may benoted that during Read Next operation; the appearance of the 4-RN signalon one of the inputs to gate 8-25 blocked its operation. The logic Iprovided at the output of gate 8-25 is operative through gates 8-13,8-14, 8-I5, and 8- 47 to produce Forward Step pulses for application tothe reader.

In contrast with the previously described usual operations, in this modeof operation the forward step pulses are repetitively generated at ahigh frequency, without reliance upon synchronizing signals RNC from theTeleprinter. These pulses recur at the repetition frequency of the ClockPulse Generator Z-CPG I. The Tape Reader stepping action will continueuntil flip-flop 8-SS is reset. The resetting of the latter flip-flop isaccomplished in the manner aforedescribed and depends upon whether ornot the Character, Word, or Line pushbutton is actuatcd.

SKIP DELETES There are times, as previously explained, when the Delete"character is used to obliterate other characters which were originallyinserted into the tape in error. In these cases, it is advantageous notto read the Delete since time is wasted. Instead, it is preferable toomit them in a manner similar to the omission operation just described.In order to effect this type of omission, a Skip/Deletes switch isprovided. This switch is shown in the upper right portion of FIG. 8. Asarranged in this embodiment of the invention, when it is desired toskip/delete characters, the switch is opened. When system is in eitherthe Run or Read Next operating modes, a logic 0 will be presentedthrough gate 8-26 to one of the inputs of gate 8-27. Another logic 0 isprovided to the input of gate 8-27 as a result of the connection throughresistor 8-29. When the Decoding circuitry detects the presence of aDelete character as the reader, the third input of gate 8-27 receives alogic 0 thereon and this results in a logic I being presented at theoutput. Gates 8-28 and 8-30 are responsive to this logic I to provide alogic 1 setting pulse to the Delete flip-flop 8-DEL.

The setting of flip-flop 8-DEL presents a logic 0 to one of the inputsof gate 8-34. Another input of gate 8-34 is supplied via gates 8-3],8-32, and 8-33. When a Delete character is detected these gates providea logic 0 enabling signal to gate 8- 34 and it thereafter passes CPIclock pulses as long as flip-flop 8-DEL remains set. The resulting logicI pulses on lead 8-35 are applied to one of the inputs of gate 8-13 andinitiate generation of Forward Step pulses at the repetition rate ofClock Pulse Generator 2-CPG 1.

After the institution of this Skip/Deletes operation, when a characterother than Delete is presented at the Tape Reader. flip-flop 8-DF is setsteered due to the removal of the logic I that the Delete signal appliedto the input of gate 8-31. At this time, the output of gate 8-31 is alogic 1. The presentation of this logic 1 to the input of gate 8-32results in the generation of a logic 0 at its output which is applied tothe set-steering lead of the Delete Finish flip-flop 8-DF. Since Deleteflip-flop 8- DEL. is in a set condition, it presents a logic 0 to oneinput of gate 8-36. The subsequently occurring CPI clock pulse thereforepasses through gate 8-36 and triggers the Delete Finish flip-flop 8-DFto a set state. Upon setting, flip-flop S-DF resets flip-flop 8-DEL vialead 8-37. This prevents the passage of further clock pulses via gate8-34 and lead 8-35. When flip- PARlTY EDIT OPERATION When a tape isdeveloped in response to received data, it conventionally includesparity codes indicating whether or not the preceding block of datasatisfies a parity check. If the block of data is correct, an ACK" codewill be inserted. If the data is incorrect, a NAK" code will beinserted. When the tape is being edited, it may be submitted to the TApeReader in reverse order so that the status character (ACK or NAK) willbe read before the associated block of data. The present inventionprovides means for selectively omitting blocks of characters which arepreceded by a NAK code.

In FIG. 8, the Parity Edit switch appears in the lower left quadrant.When this switch is open, the control system will omit data preceded byNAK characters. The decoding of a NAK character results in gate 3-38having logic at both inputs; consequently, a logic 1 appears at theoutput thereof and this is inverted by gate 3-39 and applied as the setsteering input of Omit Next Block flip-flop 8-ONB. Flip-flop 8-ONB isset upon the application of the Strobe ln signal from the Teleprinter.It will be recalled that the appearance of this signal indicates thatthe auxiliary device has received and digested the previous character.This triggering pulse provides a convenient timing pulse to assure thatthe NAK" signal has reached equilibrium prior to switching flip-flop8-ONB. When flip-flop 8-ONB is set, the logic I at its set output isapplied to gate 8-31. As in the case of the detection of a Delete signalfrom the Decoding circuitry, this results in the delivery of pulses atthe repetition rate of Clock Pulse Generator CPl over lead 8-35 to gate8-13. Accordingly, Forward Step pulses are supplied at this rapid rateto the Tape Reader. The high-speed skipping action will continue untilthe Omit Next Block flipflop 8-ONB is reset.

The resetting action is initiated by detecting the presence of an ACK"code in the tape. This code sets flip-flop 8-ACKS by placing a logic 0on the set steering input thereto. The logic 0 is applied via gates 8-43and 8-44. It will be seen that gate 8- 43 has both inputs at logic 0when flip-flop 8-0NB is in a set state and the ACI(" signal is detectedby the Decoding circuitry. When flip-flop S-ACKS is set upon occurrenceof the next Forward Step pulse, it presents a logic 0 to the input ofgate 8-45. The other input to gate 845 is a logic 0 when the presence ofan ETB" or ETX" code is detected. By. intemational standards, the lattercodes are positioned next to the ACK" code and will accordingly in thisinstance follow the ACK." Thus, a logic l signal is generatedat theoutput of gate 8-45 which sets search for NAK flip-flop 8-SFN and resetsOmit: Next Block flip-flop 8-ONB. The setting of flipflop B-SFN restoresthe Reader to normal operating conditions by applying a logic I totheset input of the Start Reader flip-flop Z-SR, thereby initiatinggeneration of the Start Reader signal.

REMOTE CONTROL OPERATION It will be appreciated that there are timeswhen the Teleprinter is being used to transmit data to a remote unit. Atthese times the data may be checked for errors at the remote site andthe coded ACK" or fNAK" signals returned to the Teleprinter to indicatesatisfactory or unsatisfactory transmission respectively. Whentransmitting from the Tape Reader, it must be stopped until the checkfor errors has occurred and then resume upon receipt of ACK." If thecheck shows an error and NAK is returned to the sender, the Reader mustbe reversedand the previous block of data reread and retransmitted.

If the Teleprinter is employing error detection, it will provide a logic1 signal labeled 9-BCCF to gate 4-22 in FIG. 48 at the time the Readeris to be stopped. This stops the Reader in the same manner as the TapeOut condition previously described.

It will be appreciated that when the Teleprinter is being operated inthis fashion, the control system will be either in a -Run or a Read Nextmode. FIG. 9 contains the principal logic elements for effecting thedesired controls in the particular situation envisaged. As shown in thisfigure, flip-flop 9-BCCR is set when the control system is in a Run modeand flip-flop 9- BCCRN is set when the system is in a Read Next mode.This is established by set steering the flip-flops with signals from theset outputs of the Run flip-flop 2-Run and the Read Next flipflop 4-RN,respectively. The BCCF signal from the Teleprinter is used as a triggersignal for these flip-flops.

1f the Teleprinter determines that it is advisable to repeat a block ofdata, it provides a reverse signal (REV) which is applied to the inputof gate 9-15. Gates 9-13 and 9-14 are appropriately interconnected tothe outputs of flip-flop 9-BCCR and 9-BCCRN so that at least one ofthese flip-flops must be set in order to provide a logic 0 output ongate 9-14. Gates 9- l4 and 9-15 both supply the input to gage 9-16. Whenboth inputs are at logic 0, gate 9-16 provides a logic 1 output which isinverted in gate 9-17 to provide a Trigger Start Reverse signal on lead9-18 which will initiate reverse stepping of the Reader. This signal isapplied to gates 2-16, 2-19 and 2-21 appearing along the left-hand edgeof FIG. 2.

1n order to prevent an endless cycle of read-error-reverse, a binarycounter is provided in the form of flip-flops 2-A and 2- B illustratedin the lower center portion of FIG. 2. F lip-flop 2- A is set onthe-first repeat of data; flip-flop 2-B is set on the second repeat ofdata. The outputs of these flip-flops are applied to ates2-16 and 2-20in order to control the effect of the Trigger Start Reverse signal onthe Tape Reader.

Assuming that the first repeat of data is requested and therefore thecounter has not achieved its maximum count, gate 2-20 will set steertheStart Reverse flip-flop Z-SREV. When the Start Reverse flip-flopZ-SREV is thus set steered, the Trigger Start Reverse signal will beapplied through inverter gate 2-19 to trigger the flip-flop into a setcondition. The resulting logic 1 signal on the set output of the StartReverse flip-flop Z-SREV is transmitted via lead 2-30 to the setinput ofReverse flip-flop 2-R. The logic I appearing at the set outputof.reverse flip-flop 2-R is then applied to gate 2-31 which also receivesan input from the set output of Back Step flip-flopZ-BSF. The resultinglogic 0 at the output of gate 2-31 is applied to the input of gate 2-32and is effective to enable this gate topass CPI clock pulses as ReverseStep pulses to the Tape Reader. .When the-tape Reader is run in reverse,it will continueto do so until the Reverse Step pulses stop. This occurswhen an-SOH" or STX" character code is detected in the tape. Thosefamiliar with the ASCII code will recognize that these character codesindicate the start of a block of data.

When one of these codes, or the reader tape out condition occurs, theoutput of gate 2-33 becomes a logic 0 and reset steers Reverse flip-flopZ-R. Flip-flop Z-R is triggered by CP2 clock pulses and thus resumes thereset condition upon the next occurring CP2 pulse. Upon resetting, thereset output of flip-flop 2-R is applied as a trigger to set Start Runflip-flop 2- SRU. The set steering of the latter flip-flop will beexplained hereinafter. .When flip-flop Z-SRU is set, it reinitiates theRun mode by setting Run flip-flop Z-RUN via gates 2-17 and 2-18.

If a second NAK" signal is received after repeating the data, this willresult in increasing the count stored in flip-flops 2-B and 2-A. Whenthe third NA1(" is received, the respective states of these counterflip-flops prevent the setting of the Start Reverse flip-flop Z-SREV andinstead enable the set input of Run flip-flopZ-RUN. Thus, the system isreturned to the Run mode without causing further reversals.

If, after a block has been transmitted, the Reader being at rest, an"ACK signal .is received from the remote unit, the Teleprinter willprovide a signal of logic 1 value at the input of gate 2-23. This iseffective to reset both counter stages Z-A and 2-B. The counter is alsoreset through gate 2-21 after it has reached the maximum allowablecount. ln the latter case, this resetting is accomplished uponcoincidence of the Trigger Start Reverse and the set condition of StartReader flip-flop 2- SR. The receipt of an "ACK signal also results inthe Teleprinter generating a forward (FWD) signal which is applied togate 9-12 in FIG. 9. The FWD signal in combination with an indicationthat the Read Next flip-flop 9-BCRN is in a reset condition and that theRun flip-flop 9-BCCR is in a set condition will result in the generationof a logic 1 signal at the output of gate 9-13 which is used to setStart Run flip-flop 2- SRU in FIG. 2.

The above-described sequence of operation assumed the equipment wasinitially in a Run mode. In the event that the equipment is in the ReadNext mode, a similar sequence of operation will occur. The differenceresides in the fact that rather than having flip-flop 9-BCCR set, theRead Next flipflop 9-BCCRN will be set. Under these conditions, thesystem will be restored to the Read Next mode by flip-flop 9-BCCRN andinterconnected flip-flop 2-SRN in FIG. 2. It is believed unnecessary tospecifically trace the details of the latter circuitry in view of thefact that all of the interconnected gates have been considered inconnection with resuming operation under the Run mode.

BACKSPACING This control system also provides for normally controlledbackspacing of the Reader. The manner in which the Reverse Step signalis generated in response to the Teleprinter command has been explained.in order to that generation of this signal within the control circuititself, the Backspace Pushbutton appearing in the lower right quadrantof FIG. 2 is provided. When this pushbutton is depressed, it appliestriggering pulses from clock pulse generator CPG l to BackspacePushbutton flip-flop Z-BSPB. The setting of the latter flip-flopprovides a trigger signal to Backspace flip-flop 2-BSF and this in turnis set. Upon being set, flip-flop 2-BSF applies a logic 1 signal to theinput of gate 231 and as previously described, this resultsin theapplication of a Reverse Step pulse to the printer at the output of gate2-32. The next occurring CPl clock pulse resets flip-flop 2-BSF and whenthe pushbutton resumes its initial position, flip-flop Z-BSPB is reset.Thus, a single step in the reverse direction is made.

in order to insure that the other modes are not disturbed during thistype of backspace operation, the output of flip-flop 2-BSF is applied tothe set input of backspace flip-flop 4-85, the latter flip-flop beingreset whenever any of the other modes are initiated.

A specific tape control system has been described and illustrated. Thistape control system was illustrated in an embodiment utilizing specificlogic circuitry in order to effect the necessary functions. It will beappreciated that those skilled in the art are capable and expected tomodify this logic circuitry in accordance with the particular needs ofthe equipment with which they are working. The scope of the invention isintended to include all modifications that come within the spirit andteachings of this disclosure.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A tape reader and control system comprising gating means controllingthe response of the system to the reading of characters on a tape,decoding means operative to detect a character on said tape and providediscrete indications representative of said character, means responsiveto said decoding means for enabling said gating means in accordance withthe particular character detected; and delay means responsive to thedetection of at least one previous predetermined character on said tapefor delaying enablement of said gating means in accordance with saidpreviously detected predetermined character.

2. A tape reader control system according to claim 1 wherein said delaymeans is effective to introduce a long delay in response to detection ofat least one previously predetermined character and a short delay inresponse to detection of at least another one previously detectedpredetermined character.

3. A tape reader and control system according to claim I, furthercomprising first and second delay means controlled by said decodingmeans to effect long or short delays, respectively, before enablement ofsaid gating means and depending upon a plurality of previously detectedcharacters.

4. A tape reader and control system according to claim 3 wherein saidfirst delay means is operative in response to detection of any one of aplurality of nonprintable characters, and said second delay means isoperative in response to detection of a given one of said plurality ofnonprintable characters only if there has not been a printable charactersince the detection of the previous given one of a plurality ofnonprintable characters.

5. A tape reader and control system according to claim 4 wherein saidplurality of characters comprises commands for mechanical operations ofconnected equipment, and a second plurality of characters comprisescommands for printing par ticular characters at said connectedequipment, said second delay means being operative in response todetection of a character of said second plurality between the detectionof a given one of said plurality of nonprintable characters and thedetection of the previous given one of said plurality of nonprintablecharacters.

6. Apparatus according to claim 1 further comprising means responsive tothe detection of at least one subsequently presented predeterminedcharacter on said tape for inhibiting the delayed enablement of saidgating means in accordance with said at least one previous characterdetected.

7. Apparatus according to claim 24 wherein said third interval is lessthan said first or second interval.

8. A tape reader and control system connected to a teleprinter, saidtape reader being operative in steps to read printable and nonprintabletape bearing characters for controlling said teleprinter, first meansfor detecting particular characters requiring nonprinting operations ofsaid teleprinter, control means for automatically advancing the tape insaid reader, delay means operative in response to said first means toinhibit operation of said control means for a first period of timesufficient for the carrying out of said nonprinting operations, meansfor selectively advancing the tape in discrete steps and presentingsuccessive characters for reading at each step, said means beingselectively inactivated upon detection of particular characters, andmeans responsive to detection of a predetermined particular character toinhibit the tape reader from reading at least one printable charactersubsequently presented.

9. A tape reader and control system according to claim 8 including meansfor advancing said reader at an accelerated rate during detection ofsaid at least one subsequently presented character.

10. A tape reader and control system according to claim 8 wherein saidmeans is automatically activated upon detection of a preselectedcharacter.

11. In a tape reader and control system connected to a teleprinter, saidtape reader being operative to advance the tape in discrete incrementsin response to a signal, each increment placing a successive code on thetape in a reading position, wherein said codes represent printablecharacters and commands to said teleprinter for printing said charactersindividually, in words, and in lines; the improvement comprising firstmeans for generating said signal one time, gating means for providingsaid signal under control of said teleprinter, detecting means fordetecting the code appearing in said reading position and providingdiscrete signal conditions upon each advance of said tape and when saidcode represents the end of a word or line, means operative to actuatesaid first means and for selectively blocking said gating means underthe control of said discrete signal conditions.

12. In a tape reader and control system according to claim 11 meansoperative when said gating means is blocked to supply said signals tosaid reader at a high repetition rate.

13. In a tape reader and control system according to claim ll, meansoperative to deactivate the tape reader when said detecting means doesnot provide a discrete signal condition upon and advance of the tape.

14. In a tape reader and control system according to claim 11, means forperiodically producing second signals that backspace the tape indiscrete increments in response to each signal, said means beingoperative in response to a signal condition from the teleprinter, meansfor terminating production of said second signals when a secondparticular code is in said reading position, and thereafter activatingsaid first means.

15. A tape reader and control system according to claim 14, wherein saidsecond signals are produced at a high repetition rate.

16. A source of information in bit parallel, character serial form,means for providing a first advance signal, means for reading out ofsaid source one character at a time in response to said first advancesignal, a printer, means for activating said printer to respond to readcharacters, said means for providing a first advance signal comprisingmeans to generate a first advance signal for enabling the reading of thenext character after the printer response is completed, means responsiveto a read character being a printable character for enabling saidprinter to respond to said read character, means responsive to said readcharacter being one of a plural number of nonprintable characters forenabling said printer to respond to said read, one of a plural number ofnonprintable characters and to generate a second advance signal forreading the next character only after a given time delay, said means forreading responsive to said second advance signal in place of said firstadvance signal to read out the next character.

17. A source of information in bit parallel, character serial form,means for reading out of said source one character at a time in responseto a control signal, a printer adapted to be enabled to respond to suchread characters, means responsive to a read character being a printablecharacter for. enabling said printer to respond to said read, printablecharacter and to provide a first control signal upon the response beingcompleted, said means for reading responsive to said first controlsignal for reading the next character after the elapse of a first timeperiod, means responsive to said read character being one of a pluralnumber of nonprintable characters for enabling said printer to respondto said read, one of a plural number of nonprintable characters and toprovide a second control signal upon the response being completed, saidmeans for reading responsive to said second control signal for readingthe next character only after the elapse of a second time period, saidmeans for readingresponsive to said second control signal in place ofsaid first control signal to read out the next character.

18. A source of information stored on tape in bit parallel, characterserial form, a tape reader, means for presenting one character at a timefrom said source to said reader in response to a control signal, aprinter adapted to be enabled to respond to such presented characters,means responsive to a presented character being a printable characterfor enabling said printer to respond to said presented, printablecharacter and to provide a first control signal upon the response beingcompleted, said reader responsive to said first control signal forreading the next character, means responsive to said presented characterbeing any one of a plural number of nonprintable characters for enablingsaid printer to respond to said presented, one of a plural number ofnonprintable characters and to provide a second control signal upon theresponse being completed, and said reader responsive to said secondcontrol signal for reading the next character only after a given timedelay.

19. A source of characters in digital form, means for presenting onecharacter at a time from said source in response to a control signal, aprinter adapted to be enabled to respond to such presented characters,means responsive to a presented character being a printable characterfor enabling said printer to respond to said presented, printablecharacter and to provide a first control signal upon the response beingcompleted, said means for presenting responsive to said first controlsignal for presenting the next character, means responsive to saidpresented character being one of a plural number of nonprintablecharacters for enabling said printer to respond to said presented, oneof a plural number of nonprintable characters and to provide a secondcontrol signal upon the response being completed, and said means forpresenting responsive to said second control signal for presenting thenext'character onlyafter the elapse of a given time delay.

20. A tape reader and control system connected to a teleprinter, saidtape reader being operative in steps to read tape bearing characters forcontrolling said teleprinter, first means for detecting particularcharacters requiring mechanical operations of said teleprinter, controlmeans for automatically advancing the tape in said reader, delay meansoperative in response to said first means to inhibit operation of saidcontrol means for a first period of time sufficient for the carrying outof said mechanical operations, second means for detecting charactersrequiring printing-by said teleprinter, and second delay means operativein response to said first means and second meanswhen said'mechanicaloperation is line feed and certain preceding characters did not requireprinting, said second delay means inhibitingoperation of said controlmeans for a period of time less than said first period.

21. A printer for responding to serially received characters comprisingmeans for responding to a given character, means for delaying saidresponse to said given character for a first time interval in responseto at least one predetermined character received prior to said givencharacter, means for delaying said responseto said given character for asecond time interval in response to at least a different onepredetermined character received prior to said given character, andmeans for delaying said response to said given character for a timeinterval different from said first and second time intervals in responseto at least one predetermined character received after said givencharacter.

22. Means for sensing in a predetermined sequence printable andnonprintable charactersstored in a storage device, means for reading insaid predetermined sequence said sensed characters, to produceelectrical signals representative of said sensed characters, meansresponsive to the reading of at least one particular nonprintablecharacter for initiating a given time delay period, means for sensingand reading in said predetermined sequence nonprintable charactersduring said time delay period until a printable character is sensed,means responsive to saidlast-named sensed printable character fordelaying further sensing and reading of characters until said time delayperiod has expired, and means for resuming sensing and reading ofcharacters in said predetermined sequence after said time delay periodhas expired.

23. An arrangement according to claim 22 wherein said at least onenonprintable character comprises a nonprintable character requiring agreater time period for execution than the longest time period betweenprinting of two successive printable characters stored in said storagedevice.

24. An arrangement according to claim 23 further comprising meansresponsive to electrical signals representative of printable charactersfor causing printing thereof and responsive to electrical signalsrepresenting nonprintable characters for executing nonprintingfunctions.

25. Means for serially sensing printable and nonprintable charactersstored serially in a storage device, means for reading saidsensedcharacters at a first rate to produce electrical signals representativeof said sensed characters, means responsive to one particular readnonprintable character for delaying reading-of the next followingprintable character for a given time period but not delaying the readingof all nonprintable characters sensed during said period before saidnext following printable character, means responsive to asecondparticular read nonprintable character immediately following saidfirst-mentioned particular read nonprintable character for reading thenext following sensed characters at a second rate as long as such nextfollowing sensed characters are said second particular nonprintablecharacters.

26. Means for serially sensing printable and nonprintable charactersstored serially in a storage device, means for reading said sensedcharacters at a first rate to produce electrical signals representativeof said sensed characters, means responsive to at least one of severalread nonprintable characters for delaying reading of the next followingprintable character for a given time period but not delaying the readingof all nonprintable characters sensed during said period before saidnext following printable character, means responsive to a predeterminedone of said several read nonprintable characters immediately followingsaid first-mentioned read nonprintable character for reading the nextfollowing sensed characters at a second rate as long as such nextfollowing sensed characters are said predetermined one of said severalnonprintable characters.

27. An arrangement according to claim 26 wherein said severalnonprintable characters comprise a line feed. a carriage return, anescape and a back space and said predetermined one of said severalnonprintable characters comprises a line feed.

28. Means for serially sensing printable and nonprintable charactersstored serially in a storage device, means for serially reading saidsensed characters to produce electrical signals representative of saidsensed characters. means responsive to at least one of several readnonprintable characters for delaying reading of the next followingprintable character for a given time period but not delaying the readingof at least one of predetermined ones of said nonprintable characterssensed duringsaid period before said next following printable character.

l l l

1. A tape reader and control system comprising gating means controllingthe response of the system to the reading of characters on a tape,decoding means operative to detect a character on said tape and providediscrete indications representative of said character, means responsiveto said decoding means for enabling said gating means in accordance withthe particular character detected; and delay means responsive to thedetection of at least one previous predetermined character on said tapefor delaying enablement of said gating means in accordance with saidpreviously detected predetermined character.
 2. A tape reader controlsystem according to claim 1 wherein said delay means is effective tointroduce a long delay in response to detection of at least onepreviously detected predetermined character and a short delay inresponse to detection of at least another one previously detectedpredetermined character.
 3. A tape reader and control system accordingto claim 1, further comprising first and second delay means controlledby said decoding means to effect long or short delays, respectively,before enablement of said gating means and depending upon a plurality ofpreviously detected characters.
 4. A tape reader and control systemaccording to claim 3 wherein said first delay means is operative inresponse to detection of any one of a plurality of nonprintablecharacters, and said second delay means is operative in response todetection of a given one of said plurality of nonprintable charactersonly if there has not been a printable character since the detection ofthe previous given one of a plurality of nonprintable characters.
 5. Atape reader and control system according to claim 4 wherein saidplurality of characters comprises commands for mechanical operations ofconnected equipment, and a second plurality of characters comprisescommands for printing particular characters at said connected equipment,said second delay means being operative in response to detection of acharacter of said second plurality between the detection of a given oneof said plurality of nonprintable characters and the detection of theprevious given one of said plurality of nonprintable characters. 6.Apparatus according to claim 1 further comprising means responsive tothe detection of at least one subsequently presented predeterminedcharacter on said tape for inhibiting the delayed enablement of saidgating means in accordance with said at least one previous characterdetected.
 7. Apparatus according to claim 24 wherein said third intervalis less than said first or second interval.
 8. A tape reader and controlsystem connected to a teleprinter, said tape reader being operative insteps to read printable and nonprintable tape bearing characters forcontrolling said teleprinter, first means for detecting particularcharacters requiring nonprinting operations of said teleprinter, controlmeans for automatically advancing the tape in said reader, delay meansoperative in response to said first means to inhibit operation of saidcontrol means for a first period of time sufficient for the carrying outof said nonprinting operations, means for selectively advancing the tapein discrete steps and presenting successive characters for reading ateach step, said means being selectively inactivated upon detection ofparticular characters, and means responsive to detection of apredetermined particular character to inhibit the tape reader fromreading at least one printable character subsequently presented.
 9. Atape reader and control system according to claim 8 including means foradvancing said reader at an accelerated rate during detection of said atleast one subsequently presented character.
 10. A tape reader andcontrol system according to claim 8 wherein said means is autOmaticallyactivated upon detection of a preselected character.
 11. In a tapereader and control system connected to a teleprinter, said tape readerbeing operative to advance the tape in discrete increments in responseto a signal, each increment placing a successive code on the tape in areading position, wherein said codes represent printable characters andcommands to said teleprinter for printing said characters individually,in words, and in lines; the improvement comprising first means forgenerating said signal one time, gating means for providing said signalunder control of said teleprinter, detecting means for detecting thecode appearing in said reading position and providing discrete signalconditions upon each advance of said tape and when said code representsthe end of a word or line, means operative to actuate said first meansand for selectively blocking said gating means under the control of saiddiscrete signal conditions.
 12. In a tape reader and control systemaccording to claim 11 means operative when said gating means is blockedto supply said signals to said reader at a high repetition rate.
 13. Ina tape reader and control system according to claim 11, means operativeto deactivate the tape reader when said detecting means does not providea discrete signal condition upon an advance of the tape.
 14. In a tapereader and control system according to claim 11, means for periodicallyproducing second signals that backspace the tape in discrete incrementsin response to each signal, said means being operative in response to asignal condition from the teleprinter, means for terminating productionof said second signals when a second particular code is in said readingposition, and thereafter activating said first means.
 15. A tape readerand control system according to claim 14, wherein said second signalsare produced at a high repetition rate.
 16. A source of information inbit parallel, character serial form, means for providing a first advancesignal, means for reading out of said source one character at a time inresponse to said first advance signal, a printer, means for activatingsaid printer to respond to read characters, said means for providing afirst advance signal comprising means to generate a first advance signalfor enabling the reading of the next character after the printerresponse is completed, means responsive to a read character being aprintable character for enabling said printer to respond to said readcharacter, means responsive to said read character being one of a pluralnumber of nonprintable characters for enabling said printer to respondto said read, one of a plural number of nonprintable characters and togenerate a second advance signal for reading the next character onlyafter a given time delay, said means for reading responsive to saidsecond advance signal in place of said first advance signal to read outthe next character.
 17. A source of information in bit parallel,character serial form, means for reading out of said source onecharacter at a time in response to a control signal, a printer adaptedto be enabled to respond to such read characters, means responsive to aread character being a printable character for enabling said printer torespond to said read, printable character and to provide a first controlsignal upon the response being completed, said means for readingresponsive to said first control signal for reading the next characterafter the elapse of a first time period, means responsive to said readcharacter being one of a plural number of nonprintable characters forenabling said printer to respond to said read, one of a plural number ofnonprintable characters and to provide a second control signal upon theresponse being completed, said means for reading responsive to saidsecond control signal for reading the next character only after theelapse of a second time period, said means for reading responsive tosaid second control signal in place of said first control signal to readout the next character.
 18. A source of information stored on tape inbit parallel, character serial form, a tape reader, means for presentingone character at a time from said source to said reader in response to acontrol signal, a printer adapted to be enabled to respond to suchpresented characters, means responsive to a presented character being aprintable character for enabling said printer to respond to saidpresented, printable character and to provide a first control signalupon the response being completed, said reader responsive to said firstcontrol signal for reading the next character, means responsive to saidpresented character being any one of a plural number of nonprintablecharacters for enabling said printer to respond to said presented, oneof a plural number of nonprintable characters and to provide a secondcontrol signal upon the response being completed, and said readerresponsive to said second control signal for reading the next characteronly after a given time delay.
 19. A source of characters in digitalform, means for presenting one character at a time from said source inresponse to a control signal, a printer adapted to be enabled to respondto such presented characters, means responsive to a presented characterbeing a printable character for enabling said printer to respond to saidpresented, printable character and to provide a first control signalupon the response being completed, said means for presenting responsiveto said first control signal for presenting the next character, meansresponsive to said presented character being one of a plural number ofnonprintable characters for enabling said printer to respond to saidpresented, one of a plural number of nonprintable characters and toprovide a second control signal upon the response being completed, andsaid means for presenting responsive to said second control signal forpresenting the next character only after the elapse of a given timedelay.
 20. A tape reader and control system connected to a teleprinter,said tape reader being operative in steps to read tape bearingcharacters for controlling said teleprinter, first means for detectingparticular characters requiring mechanical operations of saidteleprinter, control means for automatically advancing the tape in saidreader, delay means operative in response to said first means to inhibitoperation of said control means for a first period of time sufficientfor the carrying out of said mechanical operations, second means fordetecting characters requiring printing by said teleprinter, and seconddelay means operative in response to said first means and second meanswhen said mechanical operation is line feed and certain precedingcharacters did not require printing, said second delay means inhibitingoperation of said control means for a period of time less than saidfirst period.
 21. A printer for responding to serially receivedcharacters comprising means for responding to a given character, meansfor delaying said response to said given character for a first timeinterval in response to at least one predetermined character receivedprior to said given character, means for delaying said response to saidgiven character for a second time interval in response to at least adifferent one predetermined character received prior to said givencharacter, and means for delaying said response to said given characterfor a time interval different from said first and second time intervalsin response to at least one predetermined character received after saidgiven character.
 22. Means for sensing in a predetermined sequenceprintable and nonprintable characters stored in a storage device, meansfor reading in said predetermined sequence said sensed characters toproduce electrical signals representative of said sensed characters,means responsive to the reading of at least one particular nonprintablecharacter for initiating a given time delay period, means for sensingand reading in said predetermined sequence nonprinTable charactersduring said time delay period until a printable character is sensed,means responsive to said last-named sensed printable character fordelaying further sensing and reading of characters until said time delayperiod has expired, and means for resuming sensing and reading ofcharacters in said predetermined sequence after said time delay periodhas expired.
 23. An arrangement according to claim 22 wherein said atleast one nonprintable character comprises a nonprintable characterrequiring a greater time period for execution than the longest timeperiod between printing of two successive printable characters stored insaid storage device.
 24. An arrangement according to claim 23 furthercomprising means responsive to electrical signals representative ofprintable characters for causing printing thereof and responsive toelectrical signals representing nonprintable characters for executingnonprinting functions.
 25. Means for serially sensing printable andnonprintable characters stored serially in a storage device, means forreading said sensed characters at a first rate to produce electricalsignals representative of said sensed characters, means responsive toone particular read nonprintable character for delaying reading of thenext following printable character for a given time period but notdelaying the reading of all nonprintable characters sensed during saidperiod before said next following printable character, means responsiveto a second particular read nonprintable character immediately followingsaid first-mentioned particular read nonprintable character for readingthe next following sensed characters at a second rate as long as suchnext following sensed characters are said second particular nonprintablecharacters.
 26. Means for serially sensing printable and nonprintablecharacters stored serially in a storage device, means for reading saidsensed characters at a first rate to produce electrical signalsrepresentative of said sensed characters, means responsive to at leastone of several read nonprintable characters for delaying reading of thenext following printable character for a given time period but notdelaying the reading of all nonprintable characters sensed during saidperiod before said next following printable character, means responsiveto a predetermined one of said several read nonprintable charactersimmediately following said first-mentioned read nonprintable characterfor reading the next following sensed characters at a second rate aslong as such next following sensed characters are said predetermined oneof said several nonprintable characters.
 27. An arrangement according toclaim 26 wherein said several nonprintable characters comprise a linefeed, a carriage return, an escape and a back space and saidpredetermined one of said several nonprintable characters comprises aline feed.
 28. Means for serially sensing printable and nonprintablecharacters stored serially in a storage device, means for seriallyreading said sensed characters to produce electrical signalsrepresentative of said sensed characters, means responsive to at leastone of several read nonprintable characters for delaying reading of thenext following printable character for a given time period but notdelaying the reading of at least one of predetermined ones of saidnonprintable characters sensed during said period before said nextfollowing printable character.